1. Field of the Invention
This invention relates to a divided nut made of plastics which may screw on a bolt or a screw bar indivisibly.
2. Description of the Prior Art
Divided nuts of several types, which comprise a pair of divided nut parts, have been developed. As a means of screwing the divided nut on a bolt or a screw bar in such a state that the divided nut parts are connected to each other, the followings are well known. For instance, Japanese Utility Model Publication No. 50-37489 discloses that the divided nut keeps its screw fittings onto a bolt or a screw bar by holding the outer peripheries of the divided nut parts by means of a cover in such a state that the opposite surfaces of both of the divided nut parts are connected to each other. Further, British Patent No. 855,037 discloses a divided nut. Divided nut parts of the divided nut are hinged rotatably at a side portion of each of the parts. Another side of each of the parts, which sides are facing each other, provides a connectable projection having a hole. A pin is inserted into the holes of both of the projections so as to comprise an ordinary nut.
However, the divided nut of the former prior art becomes expensive as it necessitates a cover. Further, it is complex and takes time in fitting of the cover onto the divided nut while connecting the divided nut parts to each other and keeping them in its screwed position on a bolt or the like. Moreover, such a divided nut needs a means for fixing the cover so that the cover may not come off the divided nut. Further, it has a disadvantage that such a divided nut cannot be used for a screw bar which is already installed. Namely, in the case of a screw bar both ends of which are fixed to a wall or the like, both of the divided nut parts of the divided nut may be positioned on the screw bar to sandwich the screw bar from the sides thererof. However, a cover for holding the divided nut parts cannot be placed in its own position unless it is inserted to and positioned on the screw bar before fixing of the screw bar to the wall.
According to the divided nut of the latter prior art, the above mentioned disadvantages in the former prior art may be solved almost. However, when the hinge of the divided nut parts is shifted slightly in a direction of an axis of the hinge or in a direction of twist, the divided nut cannot be fit onto a bolt or a screw bar and its connection does not go in good order. Further, the divided nut is so constructed as to be able to assemble the divided nut parts by inserting the pin into the holes of the connectable projections provided with the opposite faces of another other side of each of the divided nut parts. Therefore, when a clearance is formed slightly between the pin and the holes, it cannot obtain a good screw connection as play occurrs therebetween. Further, when the pin is lost, the divided nut cannot work.
Since both kinds of the divided nuts as mentioned above, are screwed detachably onto a bolt or a screw bar, they may easily come off the bolt due to vibration or other external forces.